1. Field of Invention
The present invention relates to a surface property measuring device comprising a detector having, at a leading end thereof, a stylus for measuring surface property, typically, surface roughness. The surface property measuring device further comprising a skid, and a driving mechanism for causing the detector to advance and retreat along a surface to be measured. In particular, the surface property measuring device is capable of protecting a nose, the stylus, and the skid which protrude from the detector.
2. Description of Related Art
A surface roughness measuring device has been widely used for applying a stylus on a surface to be measured and measuring the surface roughness by detecting a surface roughness-direction-wise displacement of the stylus while advancing and retreating a detector, including the stylus, along the surface to be measured. Thus, converting the detected displacement into an electrical signal and then processing the electrical signal in a predetermined manner.
Various detectors have been proposed for the surface roughness measuring device.
For example, in FIG. 22, Japanese Patent Publication (Kokoku) No. 4-60523 shows a surface roughness measuring device 30 comprising a sliding shaft 34 held on a bearing 33, which is disposed on a frame 32 of the driving mechanism, with the sliding shaft 34 sliding in an advancing and retreating direction (arrow A) of a detector 10 . The surface roughness measuring device 30 further comprises a drivingside connector 40 attached to the sliding shaft 34 through a moving block 36 and a leaf spring 38 with a feed block 44 fixed to the sliding shaft 34 through a connecting portion 42 for causing the sliding shaft 34 to advance and retreat in the direction shown by arrow A. A feed screw 46 is then engaged with the feed block 44 with a reduction gear 50 connected to the feed screw 46 through a coupling 48, and a motor 52 for rotation-driving the reduction gear 50.
In FIG. 22, reference numeral 14 designates a detector-side connector pin attached to a rear end (on the right-hand end of the drawing) of a case 12 of the detector 10 and engaged with the driving-side connector 40. The detector 10 further includes a stylus arm 18 having a stylus 16, with a nose 26 for protecting the stylus 16 and stylus arm 18, which moves up and down while following the surface to be measured at a leading end thereof (on the left-hand end of the drawing) and swinging in the case 12 with a fulcrum 20 as a center, the leaf spring shaped substantially like an L constituting the fulcrum 20 of the stylus arm 18. An inductance type displacement detector 22 disposed in the vicinity of a rear end of the stylus arm 18 for detecting an up-and-down movement of the rear end of the stylus arm 18, with a skid 24 for absorbing minute irregularities in the vicinity of the stylus 16 to thereby obtain a stable measured value,.
Further, Japanese Provisional Utility Model Publication (Kokai) No. 5-75606, describes an arm-retracting mechanism, FIG. 23, which includes a motor 60 which rotates with a disk 62 having a notch 62A, thereby causing the notch 62A to lift a bar 68 which causes the arm 66 with a stylus 64 at a leading end thereof, to retract.
In FIG. 23, reference numeral 70 designates a fulcrum of the arm 66, with a displacement detector 72 for detecting a displacement of a rear end of the arm 66 and a friction-transmitting wheel 74 for transmitting the rotation of the motor 60 in such a manner as to slip when a load exceeds a predetermined value.
Applicant proposes in Japanese Provisional Utility Model Publication (Kokai) No. 58-76107 a receiving means comprising an instantaneous exciting latch type mechanism; for receiving, in a protecting case, a stylus protruding from a stylus protruding opening portion against the urging force of a measuring pressure applying spring.
The applicant further proposes in Japanese Utility Model Publication (Kokoku) No. 63-10481 a stylus-protecting spring for urging a stylus arm by an urging force which overcomes an urging force of a measuring pressure applying spring in such a direction as that a stylus is received in a protecting case. Kokoku further proposes an electromagnet for absorbing the stylus-protecting spring due to the energization carried out in measurement, to thereby release the stylus arm from the urging force of the stylus-protecting spring.
Also, the applicant proposes in Japanese Utility Model Publication (Kokoku) No. 63-10482 a receiving means which jointly uses a permanent magnet and a pair of coils, when measuring, which causes permanent magnet piece-side end faces of the coils to be instantaneously excited to one of an N-pole and an S-pole, thereby causing the magnet piece to be separated from a stylus arm. When not measuring, the permanent magnet piece-side end faces of the coils is instantaneously excited to the other of the N-pole and the S-pole, thereby causing the magnet piece to press the stylus arm in an opposite direction to the urging direction of the measuring pressure applying spring.
However, any one of the devices requires an independent power source such as a motor, and an electromagnet, and thus has a complicated mechanism with the reliability of the operation is likely to come into question.